Ostertag R, Hobbie Sarah E
Department of Botany, University of Florida, Gainesville, FL 32611-8526, USA, , , , , , US.
Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA, , , , , , US.
Oecologia. 1999 Dec;121(4):564-573. doi: 10.1007/s004420050963.
We examined the effects of soil nutrient availability and tissue chemistry on decomposition of both fine roots (<2 mm diameter) and leaves in three sites along a forest chronosequence in the Hawaiian Islands. These sites form a natural fertility gradient, with the youngest and oldest sites having lower nutrient availability than the intermediate-aged site. Nitrogen (N) limits aboveground net primary productivity (ANPP) in the youngest site, while phosphorus (P) limits ANPP in the oldest site. Both root and leaf litter decomposed most slowly in the 4.1-Myear-old site. We also investigated root decomposition in fertilized plots at the youngest and oldest sites; when roots were produced and decomposed in fertilized plots, root decomposition rates increased with N and P additions at the 4.1-Myear-old site. At the 300-year-old site, however, root decomposition rates did not respond to N or P additions. Roots decomposed faster than leaves at the more infertile sites, in part because of lower lignin-to-nitrogen ratios in roots than in leaf litter. Decomposing roots immobilized more nutrients than did decomposing leaves, and may serve an important role in retaining nutrients in these forests.
我们研究了土壤养分有效性和组织化学对夏威夷群岛森林演替序列中三个地点细根（直径<2毫米）和叶片分解的影响。这些地点形成了一个自然肥力梯度，最年轻和最古老的地点养分有效性低于中年地点。在最年轻的地点，氮（N）限制地上净初级生产力（ANPP），而在最古老的地点，磷（P）限制ANPP。在有410万年历史的地点，根和叶凋落物分解最慢。我们还研究了最年轻和最古老地点施肥地块中的根分解情况；当根在施肥地块中产生和分解时，在有410万年历史的地点，根分解速率随氮和磷的添加而增加。然而，在有300年历史的地点，根分解速率对氮或磷的添加没有反应。在肥力较低的地点，根比叶分解得更快，部分原因是根中木质素与氮的比率低于叶凋落物。分解的根比分解的叶固定更多的养分，可能在这些森林的养分保留中发挥重要作用。
